Two-gap spark plug with series resistor for each gap



D. E. LINDSAY July 23, 1968 TWO-GAP SPARK PLUG WITH SERIES RESISTOR FOR EACH GAP Filed May 20, 1966 INVENTOI? DONALD E LIA/05A Y y pa A WM wzmfi United States Patent "ice 3,394,285 TWO-GAP SPARK PLUG WITI-I SERIES RESISTOR FOR EACH GAP Donald E. Lindsay, Rte. 2, Box 52, Edgerton, Wis. 53534 Filed May 20, 1966, Ser. No. 551,703 4 Claims. (Cl. 315S) ABSTRACT OF THE DISCLOSURE Spark plugs having an insulator body with an annular ground electrode and a sparking electrode having a pair of semi-circular terminal heads within the annular ground electrode. A plug having a pair of sparking electrodes each having a resistor therein and a semi-circular head is also shown.

This invention relates to fuel ignitors, commonly known as spark plugs, for internal combustion engines and more particularly to new and improved anti-fouling and multiple-firing fuel ignitors.

Most known spark plugs provide a sparking gap of a very limited area such as is defined between the small tip portions of a pair of electrodes. Such spark plugs accordingly become fouled by the burning of the electrode tips and by the other corrosive effects on the electrode tips resulting from contact with hot gases in the combustion chamber of an internal combustion engine. A build up of deposits on the small tips of the electrodes after a relatively short period of use also fouls the firing and shortens the life of these known plugs. In an effort to provide a longer-lasting anti-fouling spark plug, some plugs have been provided with a sparking electrode having a disk-like terminal head concentrically located in spaced relation within a cylindrical ground electrode to provide an annular sparking gap between the ground electrode and the entire circumference of the disk-like terminal head of the sparking electrode. Thus, in this latter known type spark plug, firing may take place acrossthe annular sparking gap anywhere along its circumferential length and therefore less fouling will occur than with the first mentioned type of known spark plug. My invention relates to new and improved sure-firing fuel ignitors generally of this latter type.

An object of my invention is to provide long-lasting and anti-fouling fuel ignitors having electrodes defining adjustable elongated sparking gaps.

Another object of my invention is to provide new and improved anti-fouling fuel ignitors which areself-clean- Another object of my invention is to provide a new and improved anti-fouling fuel ignitor which is twin-firing for uniform combustion.

Another object of my invention is to provide a new and improved anti-fouling, multiple-firing fuel ignitor wherein two or more sparks may be emitted simultaneously or otherwise as desired.

Further objects, features and advantages of my invention will be apparent from the following detailed descrip tion taken in conjunction with the accompanying drawings wherein several embodiments of my invention have been selected for exemplification.

In the drawings:

FIG. 1 is a vertical section view of a fuel ignitor embodying my invention.

FIG. 2 is a bottom view of the fuel ignitor of FIG. 1.

FIG. 3 is a vertical section view of a second form of fuel ignitor embodying my invention.

3,394,285 Patented July 23, 1968 FIG. 4 is a bottom view of the fuel ignitor of FIG. 3.

FIG. 5 is a vertical section view of still another form of fuel ignitor embodying my invention.

FIG. 6 is a bottom view of the fuel ignitor of FIG. 5'.

Referring now more particularly to the drawings wherein like numerals refer to like parts throughout the several views, one form of my new fuel ignitor is shown generally at 10 in FIGS. 1 and 2. Ignitor 10 has a tubular ground electrode 11 having a generally cylindrical lower wall portion 1111. Lower wall portion 11a has external threads 12 for connecting the ignitor 10 in the conventional manner in the threaded bore of the cylinder head (not shown) of an internal combustion engine. A sealing gasket 13 of copper or the like may be provided for sealing the ignitor 10 in the cylinder head of the engine. The upper portion 11b of the tubular ground electrode 11 is provided with flats 14 forming a hexagonal head adapted to fit standard wrenches for installing and removing the ignitor 10.

As best seen in FIG. 1, an insulator body 15 extends into the tubular ground electrode 11 and a pair of sealing gaskets 16 and 17 of copper or the like may be provided for forming a seal with the Wall of the ground electrode 11. The insulator body 15 may be formed of any suitable, rigid electrical insulating, heat resistance material such as porcelain or the like.

The sparking electrode, generally designated 18, has a stern portion 19 extending through the insulator body 15. The sparking electrode 18 has a connector portion 20 extending outwardly from the top end of the insulator body 15 for connection to an ignition wire (not shown) of the internal combustion engine. The lower end of stem portion 19 has an enlarged, generally cylindrical terminal head 21 formed thereon which is concentrically disposed within the cylindrical lower portion 11a of the ground electrode 11. The terminal head 21 has an adjusting groove 21a therein dividing the head 21 into a pair of substantially semi-cylindrical terminal head segments 21b and 21c. The segments 21b and 210 thus form arcuate sparking gaps 22 and 23, respectively, with the lower portion 11a of the ground electrode 11. The ground electrode 11 may include a sleeve (not shown) inserted at the firing area and made of more suitable material than the soft metal of electrode 11 for better sparking.

As best shown in FIG. 1, the groove 21a preferably extends upwardly into the stern portion 19 of the sparking electrode 18 above the terminal head 21 whereby the terminal head segments 21b and 21c may be easily moved toward and away from each other so as to adjust the width of the arcuate sparking gaps 22 and 23. Thus, as the sparking gaps gradually widen from firing the segments 21b and 21c can be readjusted to increase the life of the plug.

The top surfaces 21d and 212 of the terminal head segments 21b and 210, respectively, may be tapered or sloped, as shown in FIG. 1, to form semi-conical shaped top portions on the terminal head segments. The cylindrical lower wall portion 11a of the ground electrode 11 together with the bottom of the insulator body 15 and the tapered or sloping top surfaces 210. and 218 of the terminal head segments 21!) and 210 define a gas chamber 24 above the terminal head segments. Upon explosion of the combustable gas mixture in the chamber 24 the emission of gases therefrom. scours and cleans those surfaces of the terminal head segments 21b and 210 and the lower wall portion 11a of the ground electrode 11 which form the sparking gaps 22 and 23. Thus, the electrodes and sparking gaps are kept clean of deposits which in conventional spark plugs tend to form on the electrodes and foul the firing thereof. The tapered surfaces 21d and 21e of the terminal head segments 21b and 21c are important in this connection in that they direct the explosion blast in gas chamber 24 outwardly through the sparking gaps 22 and 23 and across the surfaces of the electrodes 11 and 18 which define the sparking gaps.

A second embodiment of my invention is illustrated in FIGS. 3 and 4 in the form of an anti-fouling, twinfiring fuel ignitor having a tubular ground electrode 31 which is substantially the same as ground electrode 11 of ignitor 10. Ground electrode 31 has a lower wall portion 31a having external threads 32 thereon for connecting the ignitor 30 to the cylinder head of an internal combustion engine in the same manner as ignitor 10 is mounted. The upper portion 31b of the tubular ground electrode is provided with flats 33 forming a hexagonal head adapted to fit standard wrenches for installing and removing the ignitor 30.

As best seen in FIG. 3, an insulator body 34 extends into the tubular ground electrode 31 and a pair of sealing gaskets 35 and 36 of copper or the like may be provided for forming a seal with the wall of the ground electrode 31.

Ignitor 30 has a pair of sparking electrodes 37 and 38 having a pair of stem portions 39 and 40 extending through the insulator body 34. The electrodes 37 and 38 have a common connector portion 41 extending outwardly from the top end of the insulator body 34 for connection to an ignition wire of an internal combustion engine. The lower end of sparking electrode 37 has a substantially semi-cylindrical terminal head segment 42 which forms an arcuate sparking gap 43 with the lower portion 31a of the ground electrode 31. Sparking electrode 38 has an identical terminal head segment 44 which forms an arcuate sparking gap 45 with the lower wall portion 31a of the ground electrode 31. As best shown in FIGS. 3 and 4, insulator body 34 has a depending Wall portion 341: which extends downwardly between the terminal head segments 42 and 43. Preferably, the depending insulator wall portion 34a is not bonded to the terminal head segments 42 and 44 but is spaced inwardly therefrom to permit the terminal head segments 42 and 44 to be easily adjusted inwardly or outwardly to vary the Width of the respective sparking gaps 43 and 45. As with the terminal head 21 of the ignitor 10, the top surfaces 42a and 44a of the terminal head segments 42 and 44, respectively, are tapered as shown in FIG. 3 to form semi-conical shaped top portions on the terminal head segments. The cylindrical wall portion 31a of the ground electrode 31 together with the insulator body 34 and the tapered top surfaces 42a and 44a of the terminal head segments 42 and 44 define a gas chamber 46 above the terminal head segments 42 and 44 to provide a self-cleaning ignitor as described in connection with ignitor 10.

Sparking electrode 37 has a resistor 47 or other electrical component positioned in its stem portion 39 between the terminal head segment 42 and the connector portion 41. Similarly, sparking electrode 38 has a resistor 48 or other electrical component positioned in its stem portion 40 between its terminal head segment 44 and connector portion 41. The resistors 47 and 48 are preferably of the same capacity and sparking electrodes 37 and 38 each give a separate spark each time the ignitor fires. In operation, firing will normally occur across both sparking gaps 43 and 45 simultaneously to provide an even and uniform ignition. If one of the electrode gaps widens more than the other during use, the ignitor 30 will continue to fire across both gaps. The terminal head segments 42 and 44 of the sparking electrodes are easily adjusted inwardly or outwardly to provide sparking gaps of the desired width and the terminal head segments may be adjusted to provide sparking gaps of different width to provide efiicient ignition under all operating conditions. In the event that one of the electrodes 37 and 38 should become fouled, the resistor in series with the fouled sparking electrode prevents all of the electricity supplied to the ignitor 30 from being shorted out through the fouled electrode, and the second electrode will continue to provide a spark. Thus, in addition to the increased area provided in the elongated arcuate sparking gaps 43 and 45 as ignitor 10, ignitor 30 normally provides twinfiring for uniform combustion and if one electrode becomes fouled, the other continues to fire.

FIGS. 5 and 6 show a third form of fuel ignitor 50 embodying my invention. This multiple-firing form of ignitor is substantially similar to ignitor 30 except that the sparking electrodes 51 and 52 have separate connector portions 53 and 54, respectively, and the ignitor 50 need not have resistors such as are shown at 47 and 48 in ignitor 30. In this form of ignitor it is apparent that the electrodes 51 and 52 may provide sparks simultaneously or alternately and the fouling of one electrode will not hamper the firing of the other. This type of plug may also be used in a dual ignition system.

It is recognized that while in each of the exemplary ignitions illustrated only two terminal head segments are shown, two or more may be utilized, if desired without departing from the scope and spirit of my invention.

It is understood that my invention is not confined to the particular construction and arrangement of parts herein illustrated and described, but embraces all such modified forms thereof as may come within the scope of the following claims.

I claim:

1. A fuel ignitor comprising:

(a) an insulator body,

(b) a ground electrode mounted on said insulator body for mounting in an internal combustion engine,

(c) a pair of spaced sparking electrodes having a common connector extending from said insulator body for connecting said sparking electrodes to a source of electricity,

(d) a terminal head on each of said sparking electrodes adjacent said ground electrode, and

(e) means in each of said sparking electrodes for producing a voltage drop to cause said ignitor to fire between one of said terminal heads and said ground electrode when the other of said terminal heads and said ground electrode are short circuited.

2. The fuel ignitor as specified in claim 1 wherein said ground electrode is annular and said terminal heads define elongated curved sparking gaps with said annular ground electrode.

3. The fuel ignitor as specified in claim 1 wherein said means comprises a resistor in each of said sparking electrodes.

4. The fuel ignitor as specified in claim 3 wherein said ground electrode is annular and said terminal heads define elongated curved sparking gaps with said annular ground electrode.

References Cited UNITED STATES PATENTS 1,115,526 11/1914 Hagen 313- 1,560,515 11/1925 Hirsch 313-128 X 1,960,316 5/1934 Rabeffana 31558 FOREIGN PATENTS 497,516 9/1919 France. 520,794 2/ 1921 France.

DAVID J. GALVIN, Primary Examiner. 

